Green’s Dictionary of Slang

a social outcast.

1988		A. Hollinghurst Swimming Pool Library 218: Hung around in the showers--full of mutants & geriatrics.
1989		J. Doyle College Sl. Dict. 🌐 mutant [MIT] math major, especially theoretical math. Sometimes applied to theoretical physicists as well.
2003		McGill Reed Dict. of N.Z. Sl. 139: mutant Idiot; popular with teenagers.